Generally, crystalline semiconductor solar cells may be categorized as front contacted solar cells (often formed of mono and multi-crystalline silicon) or back contacted solar cells (often formed of mono-crystalline silicon). While the series resistance of conventional front contact cells tends to be dominated by the contact resistances from metal paste fire processing used to form front contact metallization, the series resistance for a back contact cell has additional components which come into play. In addition, back contact solar cell extraction is more involved/complex as compared to front contact solar cells. This is particularly the case for thinner absorber (for example less than approximately 100 um thick) back contacted solar cells where the base diffusion resistance of the silicon is also important.
Typical back contact/back junction solar components may include, for example: 1) base diffusion resistance; 2) emitter diffusion resistance; 3) base contact resistance; 4) emitter contact resistance, and 5) metal resistance. Further, a dual or multi-level metallization scheme (such as that as depicted in FIG. 1), may also comprise metal 1 (M1) to metal 2 (M2) contact resistances for both emitter and base lines, and metal 2 resistance (metal 1 and metal 2 refer to the first and the second level metallization patterns, respectively). Currently, extraction and measurement of back contacted cells, and particularly thin back contacted cells with dual level metallization, remains challenging. However, as solar cells develop, additional resistance components resulting from the addition of dual level metallization along with an increase in base diffusion resistance due to thinner films makes back contacted solar cells extraction imperative.